Hydroprocessing is any process for treating a feedstock with hydrogen. Hydroprocessing may include hydrocracking, which is a process for converting of heavy oil fractions to light oil fractions, HDS/HDN, HYD, HAD, HDM, and HDO. Hydroprocessing is taking place in a hydroprocessing catalytic reactor which is the key element of a hydroprocessing unit. Hydroprocessing catalytic reactors can have single or multiple catalyst beds. Which of the options will be chosen for a particular reactor depends on the amount of catalyst is required for conversion of the feed to the product with desired properties. Most of the hydroprocessing reactions are exothermic and heat is developed as feed is passing through the catalyst bed. In order not to expose the catalyst to higher temperatures than required, and consequently to accelerate deactivation of the catalyst, the required volume of catalyst is divided into a number of beds with cooling zones (quench sections) installed between the beds. In a radial converter, the deck of the reactor ensures that the gas flow is collected along the perimeter of the reactor prior admission to the catalyst containing section.
Due to the installation, un-installation and maintenance requirements, as well as cleaning of elements of the reactor, it is crucial to provide full access to any of the reactor elements. Outlet collectors in hydroprocessing reactors are used to collect gas and liquid at the bottom of the reactors and convey them to further processing via the outlet pipe. As the reactor is filled with catalyst, solid debris, either generated from catalyst comminution or transported with the feed stocks, may enter the outlet collector. Such debris may deposit in the outlet collector or in the outlet pipe creating increased pressure drop. Furthermore, it may be conveyed to other unit operations of the hydroprocessing unit causing adverse effect on performances of such unit operations, failure and damages to the units.
During maintenance the outlet collector and the outlet pipe need to be inspected and any debris needs to be removed. In the art, the preferred method for inspection is the removal of the outlet collector, as one piece of equipment. This is done by unfastening fixing clams and lifting the collector. Large collectors are lifted by the use of cranes. This method for accessing the outlet collector and the outlet pipe is time consuming, due to the use of tools and the crane, thereby increasing the time an operator spends in a confined space. Furthermore, it exposes the operators to a higher risk because of lifting of heavy pieces of equipment in constrained space and the use of the crane.
EP0075056 describes an ammonia synthesis system which uses at least one ammonia converter characterized by a simplified split axial flow design. An outlet collector is shown at the bottom of the converter.
CN201832617U relates to a reactor outlet collector, which is arranged on the inner side of a bottom seal head of a reactor and comprises a top cover, a cylinder and support plates. The top cover is arranged on the cylinder and covers the cylinder, the side face of the cylinder is provided with a plurality of support plates, the support plates are connected with a fixing plate through fasteners, the fixing plate is welded on the bottom seal head of the reactor, and thus the reactor outlet collector is fixed on the reactor. A positioning ring is arranged on the sidewall of the bottom seal head of the reactor and is connected with the lower end of the cylinder of the reactor outlet collector. Compared with the prior art, the utility model has the advantages that the reactor outlet collector has a simple structure, small pressure drop and smooth channels, is easy to install and the like.
CN103111239 describes a reactor comprising a cylinder, an upper seal head packaged at the top of the cylinder and a lower seal head packaged at the bottom of the cylinder, the cylinder, the upper seal head and the lower seal head form a closed cavity, reaction tubes are arranged in the cavity, the top of each of the reaction tubes is inserted to a mixed gas tank, the middle of each of the reaction tubes is inserted to a tube support, and the bottom of each of the reaction tubes is inserted to a tube plate; tube supports are fixed on the reaction tubes, the bottom of the tube plate is fixed at the top of a U-shaped cylinder, the bottom of the U-shaped cylinder is fixed on a branch tube, the bottom of the branch tube is inserted to a manifold trunk, the top of a distribution tube is inserted to the manifold trunk, the bottom of the distribution is positioned outside the manifold trunk, and the bottom of an adaptor penetrates through the lower seal head; the top of the upper seal head is provided with a work starting gas inlet; and the bottom of the lower seal head is provided with an outlet collector, and the bottom of the outlet collector is provided with a generated gas outlet. The reactor has the advantages of methanol output improvement, cost reduction, energy saving and energy consumption reduction.
CN201493096 discloses a collector for an outlet comprising a cylinder; a porous cover plate is arranged at the top end of the cylinder; uniformly distributed strip-shaped holes are axially and annularly arranged on the cylinder; a plurality of reinforcing ribs are axially and symmetrically fixed on the inner wall of the cylinder; the outer walls of the porous cover plate and the cylinder are covered with a metal grid; and the metal grid is formed by welding a plurality of support bars and grid bars perpendicular to the support bars. The collector has the advantages of simple structure, convenient installation, strong carrying capacity and the like and is mounted in a reactor, thereby fully blocking catalysts and impurities and better supporting the weight of the catalysts; and the collector is used for a long time and is not easy to block a net, so that the service life is longer.
Despite the above mentioned known art, a need exists for a reactor with an outlet collector comprising an inspection port for easy, cheap, quick and convenient maintenance, cleaning and removal of deposits of the outlet collector and of the outlet pipe.